Atlantic Sailfish – Istiophorus albicans

Rounding up our list of showstoppers is one of the fastest fish in the sea, the Atlantic Sailfish!

The Atlantic sailfish is one of 10 members of the Isiophoridae family, better known as either the Sailfish or the Billfish. Closely related to Marlin and Swordfish, there is some speculation that the Atlantic sailfish and the Indo-Pacific sailfish are in fact the same species. Let’s have a look at them!

Atlantic Sailfish

What’s in a name?

The Atlantic sailfish gets its name from the large, sail- like dorsal fin that runs along most of its back. The scientific name also reflects this, with the first part made up of two Greek words, ‘istios’ meaning sail and ‘pherein’ meaning to carry. The last part albicans comes from the Latin ‘albico’ meaning becoming white. This refers to the body colouration, which we will talk about later.

As an extra bonus fact, the name Marlin comes from a sailor’s marlinspike, which is a metal, needle-like tool used to assist tying, untying and splicing ropes.

Habitat and distribution.

As you can probably guess, the Atlantic sailfish can be found throughout the Atlantic region. It can also be found in the Caribbean, especially around the northern Yucatan peninsula and the Mediterranean. They are a highly migratory species, as juveniles have been spotted travelling from their spawning grounds around Cuba to the Mediterranean and back to Cuba to breed again. They spend most of their time in the open sea, cruising between the surface and 200m, although they prefer warmer water ranges of 25 to 30°C.

Looks that kill.

You can’t miss an Atlantic sailfish in the water! They are a large, muscular fish with a streamlined body to help them swim quickly through the water. Everything about them is designed with speed in mind. Their bodies are fusiform, which means they are tapered at both ends, perfect for streamlining.

The long rostrum, or nose, is used as both an offensive and defensive weapon but is also used as a hydrodynamic aid. How this works is to reduce the surface area of the animal as it cuts through the water, the same way as high speed rockets and jet aircraft have long pointed nose cones. The caudal fin is also strongly forked, with the same side lobes on the top and the bottom. This is another sign that the fish is a fast swimmer as other fast swimming fish show tail fins similar to this, such as the Tuna, the Wahoo and the Shortfin Mako shark.

Let’s talk about the sail! The dorsal fin is hugely extended, with 42-49 fin rays extending it along most of the fishes back. It is a dark blue with mottled black spots along its length but this colour can change with mood, excitement and temperature. The sail is approximately twice as tall as the width of the body, cutting an imposing shape in the water as it stalks prey. The fish is also able to lower the sail flat against its body or to the side, again to aid in streamlining and hydrodynamics.

The colour of the body, much like the dorsal sail, changes depending on the excitement of the fish. It is normally a rich, dark blue blending into a silvery underside in a classic example of counter shading (camouflage against the light from above and below). Along their sides they have 20 stripes of dark blue, between which are many small, light blue spots. As it gets more excited chasing prey, however, the fish flash darker blue to black, browns or even dark reds. This is caused by blood flushing to the skin and is a great way to tell if the fish is in hunting mode or not.

Lifestyle choices.

Atlantic Sailfish are broadcast spawners, releasing eggs and sperm into the water column to mix and drift away. They spawn all year round but it is most common in the summer months when the water is warmer, with Cuban waters being a popular breeding site. Close to the surface in shallow water, the female will swim with her sail extended above the surface to attract the males. Males will race each other and chase the female, with the fastest male winning the breeding rights. The other males will still spawn, trying to hopefully fertilize as many eggs as they can. She will release her eggs where one or more males will fertilise the eggs. The females can release up to 4.8 million eggs per spawn, usually in three batches.

The small sailfish hatch out without their characteristic sails and long snouts but very quickly, by the time they are at around 5cm, the sails and snouts are there. Looking like tiny versions of their adult selves, they are already streamlined, fast moving hunting machines.

Life on the reef.

As I said earlier, sailfish do not live on the reef! They are an open ocean, transient species spending most of their time in the top 10m where the water is warmest. During this time, they have a cruising speed of approximately 30km/hr and keep their sails slightly folded. This is where they chase shoals of their favourite foods; mackerels, sardines, anchovies and squid.

Once they find a shoal, they corral the prey into a ball before dropping the sail and swimming quickly into them. They then thrash their bills around to either bash and stun or slash the prey before consuming them. The speed of their attack has been measured at up to 110km/hr! Swimming at these speeds keeps their muscles nice and warm, which allows them to spend time in deeper, colder water to hunt alongside the surface. However, if they are starting to overheat, they raise the sail out of the water and flush it with blood. This cools if and allows the fish to maintain a constant body temperature a few degrees above the surrounding water.

As an alpha predator, sailfish have few natural predators. They are, however, a staple of the game fishing industry as they put up a fight when caught. This catch can tire out the fish and overheat it, meaning that even after they are released they usually die.

They live for approximately 15 years and reach sexual maturity at around 3 to 4 years. Full size for an adult, including the rostrum, is 315cm with the largest published weight being 58kg.

Personal experiences.

Don’t bother trying to dive with a sailfish, you’ll never be able to keep up with them! The best way to see these amazing animals is snorkelling, that way you can swim with them and then jump back in the boat to chase. The boat operators use the latest fish scanning technology used by commercial fishermen to track their movements so you always stay one step ahead. It is a good idea to stay a respectful distance from the Atlantic sailfish as while they are not an aggressive species, they are a large, powerful animal and the snout spike can cause serious injuries. Never try to get in and amongst the sailfish as they are feeding, you are just asking for trouble! Keep your fins and mask on when you are on the edge of the boat and be ready to swim!

The bottom line.

Atlantic sailfish are a once in a lifetime encounter. Most people will never see them, unless you are super lucky and they appear out of the blue on a dive. During the right season (from December to March), day expeditions can be taken to go hunting for them. We travelled with Prodive Mexicoto see them and stayed at the Allegro in Playacar. This is also a great place to access the cenotes and cave dives, my favourite dives in the world! If you would like somewhere a bit more intimate and quiet, why not try the Kinbe hotel in Playa del Carmen or for easy access to Whale shark snorkelling try the Paradise divers in Isla Mujeres.

A short as the window is, you would be crazy to miss an opportunity to see these amazing creatures. Stunning to look at and amazingly quick, the Atlantic sailfish provides an intense and unique experience. Don’t miss out!

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